The present disclosure relates to removal of deposits from a substrate, such as an imaging member. It finds particular application in conjunction with removal of a lateral charge migration film from a photoconductive receptor belt, and will be described with particular reference thereto. However, it is to be appreciated that the present disclosure is also amenable to other like applications.
In an electrophotographic application such as xerography, a charge retentive surface (i.e., photoconductor, photoreceptor, or imaging surface) is electrostatically charged and exposed to a light pattern of an original image to be reproduced to selectively discharge the surface in accordance therewith. The resulting pattern of charged and discharged areas on that surface form an electrostatic charge pattern (an electrostatic latent image) conforming to the original image. The latent image is developed by contacting it with a finely divided electrostatically attractable powder referred to as “toner.” Toner is held on the image areas by the electrostatic charge on the surface. Thus, a toner image is produced in conformity with a light image of the original being reproduced. The toner image may then be transferred to a substrate (e.g., paper), and the image affixed thereto to form a permanent record of the image to be reproduced. Subsequent to development, excess toner left on the charge retentive surface is cleaned from the surface. This process is known, and useful for light lens copying from an original, and printing applications from electronically generated or stored originals, where a charged surface may be image-wise discharged in a variety of ways. Ion projection devices where a charge is image-wise deposited on a charge retentive substrate operate similarly.
Electrophotographic imaging members are commonly multilayered photoreceptors that include a substrate support, an optional electrically conductive layer, an optional charge blocking layer, an optional adhesive layer, a charge generating layer, a charge transport layer, and an optional protective or overcoating layer(s). The imaging members can take several forms, including flexible belts, rigid drums, and the like.
Electrophotographic machines utilizing multilayered organic photoreceptors employ corotrons or scorotrons to charge the photoreceptors prior to exposure of an image. During the operating lifetime of photoreceptors, they are subjected to corona effluents which include ozone, various oxides of nitrogen, and the like. In the presence of volatile organic chemicals and water, a reaction occurs between the corona effluents. Over time, an electrically conductive film may develop on the photoreceptor belt.
Furthermore, during operation of the electrophotographic machine, a region of the top surface of the photoreceptor, such as a photoreceptor belt, is continuously worn away, thereby preventing or limiting accumulation of the conductive film. However, when the machine is not operating (i.e., in idle mode), for example, between two large copy runs, or at any time when the belt is moving but unprotected by toner, a conductive film can develop. In the idle mode, a portion of the photoreceptor comes to rest beneath a corotron. Although the high voltage to the corotron is turned off during the time period when the photoreceptor is stationary, some effluents (e.g. nitric acid, etc.) continue to be emitted from the corotron shield and corotron housing. This effluent emission is focused on the portion of the photoreceptor directly beneath the corotron, increasing the conductivity of the surface. When machine operation is resumed for the next copy run, image spreading and loss of resolution tends to occur in the region of the photoconductor where surface conductivity has increased, known as lateral charge migration (LCM). Deletion may also be observed in the loss of fine lines and details in the final print. Loss of resolution along the entire imaging surface can also occur due to an increase in surface conductance caused by corona species interaction. In the case of excessive increases in conductivity, there can be regions of extreme deletions in the images. This problem is particularly severe in devices employing arylamine charge transport molecules such as N,N′-diphenyl-N,N′-bis(3-methylphenyl)-(1,1′-biphenyl)-4,4′-diamine and charge transport polymers incorporating diamine transporting moieties.
The common solution to the problem of LCM deposits has been to replace the photoreceptor belt, resulting in down time of the imaging device.
U.S. Pat. No. 6,361,913 to Pai, et al. discloses a long life photoreceptor having improved resistance to corona effluent induced deletions. The photoreceptor comprises a substrate, a charge generating layer, a charge transport layer, and an overcoat layer. The overcoat layer comprises a hydroxy triphenyl methane having at least one hydroxy functional group and a polyamide film forming binder capable of forming hydrogen bonds with the hydroxy functional group. The charge transport layer is substantially free of triphenyl methane molecules.
There remains a need for a method of removal of residues, such as LCM films, from electrophotographic imaging members. Furthermore, there is a continuing need for an improved system for removing residues, such as those comprising morpholine derivation and/or the reaction products of corona effluents with volatile organic chemicals, from photoreceptors.